function s1_goto_dir(){

    cd "$1" || exit 1
}

function s2_touch_empty_file_with_given_name(){

    touch "$1"
}

function s3_make_directories(){

    mkdir projects
    cd projects
    mkdir git
    mkdir backup
}

function s4_create_6_files(){

    touch projects/linux{1,2}_{centos,redhat,c_programming}
}

function s5_make_directories_in_git(){

    mkdir  projects/git/linux1 projects/git/linux2
}

function s6_move_files_to_dir_1_or_2(){

    mv projects/linux1_* projects/git/linux1/ 
    mv projects/linux2_* projects/git/linux2/
}

function s7_create_package_and_compress(){
    
    cd projects
    tar -czvf backup/git.tar.gz git/
}

function s8_delete_dir_git(){

    rm -rf projects/git/
}

function s9_recover_from_git_tar_gz_backup(){

    tar -zxvf projects/backup/git.tar.gz -C ./projects/
}

function s10_create_package_and_compress(){

    cd projects
    tar -jcvf backup/git.tar.bz2 git/
}

function s11_find_and_sort_alphabetically_all_created_files_and_dirs(){

    find ./projects -type f -o -type d | sort
}

function s12_get_next_15_minutes_boundary(){

    current_timestamp=$(data +%s)
    rounded_timestamp=$(( (current_timestamp + 750) / 900 * 900 ))
    current_timetamp=$(date +%s)
    interval_start_timestamp=$(( (current_timestamp / 900) * 900))
    next_interval_timestamp=$(( interval_start_timestamp + 900))
    next_15min_boundary=$(date -d @"$next_interval_timetamp" +%Y-%m-%d_%H:%M:%S)
    echo "$next_15min_boundary"
}
